The present invention relates to poly(5-aminoquinoxalines) which have excellent thermal resistance, permits easy control of electrochemical oxidation-reduction potential, has a very narrow band gap of itself and has strong fluorescence characteristics, and application of the same.
These polymers have an electron-donating group and an electron-accepting group in one molecule thereof, whereby they have p-type and n-type semiconductor characteristics. These compounds can easily be formed into a thin film by the spin coating method, and can be applied as an active substance or an electrode material for a battery, an organic electroluminescence device material, an electroluminescence device material, a semiconductor, a semiconductor device, and a nonlinear-type optical material.
In recent years, aromatic compounds with a xcfx80 conjugated system spread in two dimensions and heterocyclic compounds having a hetero-atom have been used for a variety of electronic devices through utilization of their light emission characteristics and electron and positive hole transport characteristics. For example, organic electroluminescence devices are generally classified into high polymeric devices utilizing the xcfx80 conjugated system and low molecular weight devices with various functions separately possessed by layers which are laminated. Particularly, in the case of the low molecular weight materials, there has been a requirement for their carrier mobility and fluorescence characteristics, and it has been required to freely change the band gap in developing derivatives thereof. In addition, for these materials, film characteristics thereof are important, and they have been demanded particularly to form a stable amorphous film (Polymer, 24(1983), p. 748; Jpn. J. Appl. Phys. 25(1986), L773; Appl. Phys. Lett. 51(1987), P. 913; U.S. Pat. No. 4,356,429).
In the battery, also, there is a demand for control of the oxidation and reduction potentials of the compound (for example, Denki Kagaku Oyobi Kogyo Butsuri Kagaku (Electrochmistry and Industrial Physical Chemistry), Vol. 54, p. 306 (1986)). As to the electrode active substance used in the battery, in relation to the electrolyte, it is necessary to set the oxidation-reduction potential of the substance to within the dessociation voltage of the electrolyte, and, therefore, control of the oxidation-reduction potential has been an important problem.
As for the semiconductor characteristics, xcfx80 conjugated system polymers have been investigated for the purpose of achieving a narrower band gap, but, generally, the xcfx80 conjugated system polymers are insoluble in solvents and are difficult to deal with, and it has been difficult to control the structure of the polymers. In addition, as another method of narrowing the band gap, there is a method of spreading the xcfx80 conjugated system in two dimensions (Synthetic Metals, 69(1995), pp. 599-600; J. Am. Chem. Soc. 177(25), 1995, pp. 6791-6792), but these materials are also insoluble and infusible and are inconvenient to deal with. Besides, general xcfx80 conjugates system polymers can display behaviors as an impurity semiconductor upon being doped with an impurity, but it has been difficult to stably form p-type and n-type semiconductors from one substance.
The present invention has been completed based on the results of earnest studies in search of a compound having a novel molecular structure, in consideration of the above circumstances. Accordingly, it is an object of the present invention to provide poly(5-aminoquinoxalines) which have excellent thermal resistance, are soluble in water or an organic solvent, permit control of degree of depolarization and electrochemical oxidation-reduction potential thereof, show a clear color change due to chemical or electrochemical oxidation or reduction, and are themselves electrically conductive.
It is another object of the present invention to utilize such novel poly(5-aminoquinoxalines) as an organic electroluminescence device, an electrochromic device, an active substance or an electrode for a battery, a semiconductor, an n-type semiconductor, a solar-cell electrode, a non-linear device, etc., by forming the novel poly(5-aminoquinoxalines) into a film or the like through the spin coating method or the like.
In accordance with one aspect of the present invention, there is provided a poly(5-aminoquinoxaline) having the general formula (1): 
in which R1 and R2 each independently represent a hydrogen atom, a hydroxyl group, a phenyl group, a substituted phenyl group, a biphenyl group, a substituted biphenyl group, a thienyl group, a substituted thienyl group, a naphthyl group, a substituted naphthyl group, a pyrrolyl group, a substituted pyrrolyl group, furyl group, a substituted furyl group, an alkyl group, or an alkoxyl group; R3 and R4 each independently represent a hydrogen atom, an alkyl group, an alkoxyl group, a cyano group, a phenyl group, a substituted phenyl group, a biphenyl group, a substituted biphenyl group, a thienyl group, a substituted thienyl group, a pyrrolyl group, a substituted pyrrolyl group, a furyl group, a substituted furyl group, a naphthyl group, or a substituted naphthyl group; R5 represents a hydrogen atom, an alkyl group, an alkoxyl group, an acetyl group, a thienyl group, a substituted thienyl group, a pyrrolyl group, a substituted pyrrolyl group, a naphthyl group, or a substituted naphthyl group; and n represents a positive integer of not less than three.
In the general formula (1) above, R1 and R2 may independently be groups having the general formula (2): 
in which R7 to R11 each independently represent a hydrogen atom, a halogen atom, a cyano group, an amino group, a cyanoalkyl group having one to four carbon atoms, a haloalkyl group having one to four carbon atoms, an alkyl group having one to ten carbon atoms, an alkoxyl group having one to ten carbon atoms, a nitro group, a phenyl group, a substituted phenyl group, a biphenyl group, a substituted biphenyl group, a naphthyl group, a substituted naphthyl group, a thienyl group, a substituted thienyl group, an epoxy group, or a vinyl group.
In the general formula (1) above, R1 and R2 may independently be groups having the general formula (3): 
in which either one of R12 to R19 is coupled to the quinoxaline ring; and the others of R12 to R19 each independently represent a hydrogen atom, a halogen atom, a cyano group, an amino group, an alkyl group having one to ten carbon atoms, an alkoxyl group having one to ten carbon atoms, a nitro group, a phenyl group, a substituted phenyl group, a biphenyl group, a substituted biphenyl group, a naphthyl group, a substituted naphthyl group, a thienyl group, a substituted thienyl group, an epoxy group, or a vinyl group.
In the general formula (1) above, R1 and R2 may independently be groups having the general formula (4): 
in which either one of R20 to R23 is coupled to the quinoxaline ring; the others of R20 to R23 each independently represent a hydrogen atom, a halogen atom, a cyano group, an amino group, an alkyl group having one to ten carbon atoms, an alkoxyl group having one to ten carbon atoms, a nitro group, a phenyl group, a substituted phenyl group, a biphenyl group, a substituted biphenyl group, a naphthyl group, a substituted naphthyl group, a thienyl group, a substituted thienyl group, an epoxy group, or a vinyl group; and A represents NH, O, or S.
In the general formula (1) above, R1 and R2 may independently be groups having the general formula (5): 
in which R24 represents a halogen atom or a cyano group; and R25 to R28 each independently represent a halogen atom, a cyano group, an amino group, an alkyl group having one to ten carbon atoms, an alkoxyl group having one to ten carbon atoms, a nitro group, a phenyl group, a substituted phenyl group, a naphthyl group, a substituted naphthyl group, a thienyl group, a substituted thienyl group, an epoxy group, or a vinyl group.
In the general formula (1) above, R5 may be a group having the general formula (6): 
in which R29 to R33 each independently represent a hydrogen atom, a halogen atom, a cyano group, an amino group, an alkyl group having one to ten carbon atoms, an alkoxyl group having one to ten carbon atoms, a nitro group, a phenyl group, a substituted phenyl group, a naphthyl group, a substituted naphthyl group, a thienyl group, a substituted thienyl group, an epoxy group, or a vinyl group.
In the general formula (1) above, R5 may be a group having the general formula (7): 
in which R34 to R36 each independently represent a hydrogen atom, a halogen atom, a cyano group, an amino group, an alkyl group having one to ten carbon atoms, an alkoxyl group having one to ten carbon atoms, a nitro group, a phenyl group, a substituted phenyl group, a naphthyl group, a substituted naphthyl group, a thienyl group, a substituted thienyl group, an epoxy group, or a vinyl group; and Z represents NH, O, or S.
In the general formula (1) above, R5 may be a group having the general formula (8): 
in which R37 to R39 each independently represent a hydrogen atom, a halogen atom, a cyano group, an amino group, an alkyl group having one to ten carbon atoms, an alkoxyl group having one to ten carbon atoms, a nitro group, a phenyl group, a substituted phenyl group, a naphthyl group, a substituted naphthyl group, a thienyl group, a substituted thienyl group, an epoxy group, or a vinyl group; and Q represents NH, O, or S.
In the general formula (1) above, R5 may be a group having the general formula (9): 
in which R40 to R46 each independently represent a hydrogen atom, a halogen atom, a cyano group, an amino group, an alkyl group having one to ten carbon atoms, an alkoxyl group having one to ten carbon atoms, a nitro group, a phenyl group, a substituted phenyl group, a naphthyl group, a substituted naphthyl group, a thienyl group, a substituted thienyl group, an epoxy group, or a vinyl group.
In accordance with another aspect of the present invention, there are provided applications of the poly(5-aminoquinoxaline) represented by the general formula (1) above. The applications of the poly(5-aminoquinoxaline) of the general formula (1) reside in: a film formed by spin coating or casting of a poly(5-aminoquinoxaline) of the formula (1); a film formed by compression molding of a poly(5-aminoquinoxaline) of the formula (1); an electrochromic device including a poly(5-aminoquinoxaline) of the formula (1); an active substance or an electrode for a battery, including a poly(5-aminoquinoxaline) of the formula (1); a semiconductor including a poly(5-aminoquinoxaline) of the formula (1); a p-type semiconductor produced by oxidizing a poly(5-aminoquinoxaline) of the formula (1) by an oxidant or electrochemical doping; an n-type semiconductor produced by reducing a poly(5-aminoquinoxaline) of the formula (1) by a reducing agent or electrochemical doping; a solar cell comprising the p- and n-type semiconductors; an organic electroluminescence device including a poly(5-aminoquinoxaline) of the formula (1); and a non-linear organic material including a poly(5-aminoquinoxaline) of the formula (1).
The novel poly(5-aminoquinoxalines) according to the present invention have good thermal resistance and are soluble in water or organic solvents. Therefore, the polymers find a wide range of utilization, and can be dry formed into fibers, films and the like by utilizing solutions obtained by dissolving the polymers in appropriate solvents. In addition, due to the structure thereof, the novel polymers according to the present invention have excellent properties that are not possessed by the conventional polyarylenes; for example, the polymers of the invention permit control of the degree of depolarization and the electrochemical oxidation-reduction potential thereof. Besides, according to the method of the present invention which will be described later, it is possible to obtain a polymer in which electric charges are localized along the xcfx80 conjugated system. In addition, the polymers according to the present invention themselves are electrically conductive.
The above and other objects, features and advantages of the present invention will become apparent from the following description of the preferred embodiments and appended claims of the invention.